Vehicles with engines may include transmission systems, e.g., automatic transmission systems, which may adjust a transmission gear ratio in response to engine operating conditions, e.g., in response to changes in vehicle speed, engine speed, vehicle and engine loads, accelerator pedal position, shift lever/paddle position, etc. During some conditions, e.g., in response to an increased vehicle speed, an automatic transmission system may initiate an upshift from a first gear ratio to a second, lower gear ratio. A driver's perception of the duration of an upshift on a transmission may be largely based on visual information received from an engine RPM display device, e.g., a tachometer, and audible indications of a change in engine speed, e.g., changes in audible engine frequencies. For example, during a slowly changing accelerator pedal position, a well-executed upshift may result in very little disturbance in output shaft torque or seat track acceleration. The actual shift has a torque phase and an inertia phase, where the engine speed and transmission speed ratio change during the inertia phase.
However, the inventors herein have recognized that during some conditions a driver may desire quick, smooth, and/or consistent upshifts, especially at high pedal demand, when in ‘sport’ mode, or when driving transmissions that are marketed as being sporty, for example. The perceived quickness of the shifts is related to the duration of the inertia phase of the gear shift. The powertrain behavior during the inertia phase may be limited and may vary based on engine operating conditions, vehicle loads, engine calibration, emissions constraints, and other factors that will vary from application to application or over time in a given vehicle.
Further, an RPM display device in a vehicle, e.g., a tachometer, may have delays in displaying a current engine RPM to a driver of the vehicle, e.g., during a gear shift. For example, mechanical delays may cause a tachometer to report a delayed or lagged engine RPM to a driver during a gear shift change. Further still, in some examples, various filters may be applied to a signal provided to an RPM display device to reduce noise or other disturbances in the signal so that a clearer or more consistent indication of RPM may be displayed to a driver. However, such filters may cause further delays in indicating a current RPM of the engine during a shift change, for example. Thus, it may be desirable to have a continuous, consistent, and smooth display of engine RPM to the driver in order to increase a satisfaction of the driver with vehicle and engine performance.
In one example approach, to at least partially address these issues, a method for a vehicle comprises, during a transmission shift having a first engine speed profile, adjusting a transmission shift indication provided to a vehicle operator based on a desired perceived shift time and a desired engine deceleration rate. For example, an engine speed profile displayed to the vehicle operator and/or a transmission shift noise profile provided to the vehicle operator may be adjusted.
In this way, engine performance during a gear shift may be indicated to a driver in a quick, smooth, and/or consistent way, particularly during a high accelerator pedal demand. For example, a duration of the inertia phase as displayed to a driver may be adjusted. Further, delays in indicating engine speed changes to a driver may be reduced to provide a clearer or more consistent indication of engine RPM response as displayed to a driver. For example, the engine speed as displayed on the tachometer may be adjusted to reflect a desired engine speed profile during an upshift so that the engine speed drops in a quick, consistent way. Further, in some examples, an engine sound profile at the driver's ear may be adjusted to reflect changes in engine frequencies corresponding to engine deceleration during the inertia phase. For example, the engine sound provided to a driver may be adjusted to match the profile displayed on the tachometer. In this way, clear, quick, smooth, and consistent indications of engine performance during a gear shift may be indicated to a driver while controlling the powertrain for tactilely smooth, robust shifts to increase a satisfaction of the driver with vehicle and engine performance.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.